1. Field of the Invention
The present invention relates to a discharge nozzle processing method of using ultraviolet lasers for sublimating and processing a discharge nozzle in a liquid jet recording head for ejecting liquid droplets such as recording liquid droplets, thereby depositing the liquid droplets. Further, the present invention relates to a method for manufacturing the liquid jet recording head.
2. Related Background Art
In a liquid jet printing apparatus (an ink jet printer) for jetting recording liquid droplets such as ink, thereby depositing the liquid droplets on a recording medium, print quality greatly depends on characteristics of a nozzle portion for discharging the recording liquid. The characteristics of the nozzle portion are substantially determined depending on variations in the nozzle diameter or shape of the nozzle. Two methods for forming a nozzle are employed. There has been proposed a method for forming the nozzle using an electric casting technique employing a metal plate or an electric discharge processing technique, and a method for sublimating and processing (abrasion) an organic polymer resin material by means of high energy lasers such as ultraviolet-ray lasers represented by excimer lasers. At present, the latter, a fine processing method employing ultraviolet-ray lasers, is generally employed.
In this ultraviolet-ray laser processing method, when processing is carried out at an energy density of lasers preferable for sublimating and processing an organic polymer resin material, there are provided so called taper-shaped processing characteristics in which a processing area gradually decreases from the laser incident side to the laser emission side. In addition, the shape of the nozzle required to improve the print quality of the liquid jet recording head is a divergent taper-shape on a recording liquid ejection side. Thus, the laser processing method is carried out by laser emission from a recording liquid supply side. That is, there has been adopted a process for bonding a plate for forming the discharge nozzle to a member for supplying a recording liquid, after processing and forming the discharge nozzle.
However, the length of the discharge nozzle is required to be about 10 microns to about 100 microns in view of print quality. Of course, the ejection orifice forming plate which forms this discharge nozzle has a thickness similar to the above. This ejection orifice forming plate is a very thin and easily deformed member. The plate must be laser-processed from the liquid supply side to the ejection orifice forming plate, and must be bonded to a member for supplying the recording liquid, after processing and forming the discharge nozzle. Thus, there has been a problem that the ejection orifice forming plate is stress-deformed after bonding, a plurality of discharge nozzles arranged in one direction cannot be formed, and the recording liquid is discharged randomly, thereby degrading the print quality.
In order to solve this problem, there have been proposed methods for processing the discharge nozzle after the liquid jet recording head has been assembled. One is a method proposed in National Publication of International Patent Application No. 6-510958 (Compaq Computer Corporation). In this method, light beams restricted by a mask pattern are obliquely made incident on the ejection orifice forming plate in two directions. By making light beams obliquely incident thereto, the ejection orifice forming plate is processed in the forward direction of the light beams. As a result, the discharge nozzle is formed in a wider taper shape with its wide processing width being inward from the outside.
The other is a method proposed in Japanese Patent Publication No. 6-24874 (Zarl Limited). In this method, light beams are emitted in the form that a mask plate having a nozzle pattern formed thereon is brought into close contact with the ejection orifice forming plate. Then, the light beams are subjected to swinging or pivoting motion so as to be obliquely incident to the closely contacted mask plate and the ejection orifice forming plate. Further, processing advances in the light beam incident direction, thereby forming a convergent taper-shaped nozzle at the liquid ejection side of the ejection orifice forming plate.
However, in the aforementioned method described in National Publication of International Patent Application No. 6-510958, although a convergent tapered shape is formed at the liquid ejection side of the ejection orifice forming plate with respect to the obliquely incident direction of light beams because of its light beam processing in two directions only, a divergent tapered shape is formed at the liquid ejection side in a direction vertical thereto. In this way, a cone-shaped taper symmetrical to the liquid ejection direction is not formed, and thus, a recording liquid ejection fluid resistance occurs with the liquid ejection side in the divergent taper shape. As a result, the period of liquid ejection is delayed, thus preventing fast printing. Further, in the case of a divergent nozzle shape, there occurs a problem that a mist is generated during liquid ejection.
Furthermore, since this is not a mask pattern projection image forming system, discharge nozzles must be processed individually one by one. Thus, in the case where a very large number of discharge nozzles must be formed, there has been a problem that the processing time increases, which is disadvantageous as to productivity. Moreover, there has been a problem that the nozzle processing size is varied sensitively to the light beam energy strength, which causes difficulty in stability in processing accuracy.
In addition, in the aforementioned method described in Japanese Patent Publication No. 6-24874, a mask plate and an ejection orifice forming plate are subjected to a motion for these plates to be inclined to light beams with an elapse of time. This makes it difficult to process a taper shape symmetrical to the liquid ejection direction axis depending on the processing start state and processing end state, namely, depending on the processing operation process based on an elapse of time. As a result, there has been a problem that it is difficult to eject the recording liquid stably in a constant and uniform direction for each of individual liquid jet recording heads.
In order to solve the aforementioned problems, a method has been proposed in Japanese Patent Application No. 10-182407 for bringing a mask plate whose ejection orifice shape is patterned into close contact with an exterior face of an ejection orifice forming plate at which a plurality of liquid jet recording head ejection orifices are formed in a one-dimensional arrangement or a plurality of arrangements are formed; and simultaneously emitting a plurality of parallel ultraviolet-ray beams with high energy in a direction obliquely inclined by a predetermined angle with respect to a vertical axis of the mask plate face and in a rotationally symmetrical direction, thereby sublimating processing, and forming a discharge nozzle at an ejection orifice forming plate.
The discharge nozzle formed by this method is shaped to be symmetrical to the liquid ejection direction axis; the partially or entirely convergent tapered shape can be formed at the liquid ejection side of the ejection orifice forming plate; and a number of discharge nozzles can be batch processed for a short time. However, further technical improvements are expected in that the emitted light beam strength distribution is made uniform and symmetrical in a full processing area, and a plurality of discharge nozzles to be processed is formed in a uniform shape.
It is one object of the present invention to provide a method for processing a discharge nozzle for processing and forming a partially or entirely taper-shaped discharge nozzle at a liquid ejection side by means of laser processing with laser beam emission from a liquid ejection side of an ejection orifice forming plate, the discharge nozzle processing method being capable of uniformly processing all the ejection orifice nozzle shapes and constantly and accurately jetting recording liquid droplets, and further, to provide a liquid jet recording head manufacturing method capable of improving print quality.
It is another object of the present invention to provide a method for processing a discharge nozzle of a liquid jet recording head for bringing a mask plate on which the shape of an ejection orifice to be formed is patterned into close contact with the liquid ejection side of an ejection orifice forming plate on which a plurality of ejection orifices of a liquid jet recording head are formed, and emitting parallel laser beams from the mask plate side, thereby processing and forming a discharge nozzle at said ejection orifice forming plate, wherein the closely contacted mask plate and the ejection orifice forming plate are reciprocally scanned by one reciprocation or more along an arrangement for forming discharge nozzles with respect to a laser beam emission area.
In a method for processing a discharge nozzle of a liquid jet recording head according to the present invention, it is preferable that emissions of parallel ultraviolet-ray laser beams with high energy are arranged so as to be incident simultaneously in plurality in a direction obliquely inclined by a predetermined angle with respect to the vertical axis of the mask plate. In addition, it is preferable that emissions of parallel ultraviolet-ray laser beams with high energy are arranged simultaneously in a direction equally divided with respect to the peripheral direction of the vertical axis of the mask plate.
In a method for processing a discharge nozzle of a liquid jet recording head according to the present invention, it is preferable that parallel ultraviolet-ray laser beams with high energy each are composed of four luminous fluxes, and are emitted simultaneously in a direction equally divided with respect to the peripheral direction of the vertical axis, the beams each being inclined at a predetermined angle with respect to the vertical axis of the mask plate.
It is a still another object of the present to provide a method for manufacturing a liquid jet recording head for bringing a mask plate on which the shape of an ejection orifice to be formed is patterned into close contact with the liquid ejection side of an ejection orifice forming plate having a plurality of ejection orifices formed thereon after at least the ejection orifice forming plate and a member for holding the ejection orifice forming plate have been coupled with each other from among members constituting the entire liquid jet recording head, and simultaneously emitting a plurality of parallel laser beams in a direction inclined at a predetermined angle with respect to a vertical axis of the mask plate face, thereby processing and forming a discharge nozzle at the ejection orifice forming plate, wherein the closely contacted mask plate and the ejection orifice forming plate are reciprocally scanned by one reciprocation or more along an arrangement for forming the discharge nozzles with respect to the emission area of the laser beams.
In a method for manufacturing a liquid jet recording head according to the present invention, it is preferable that emissions of a plurality of ultraviolet-ray laser beams with high energy are arranged so as to be incident in a direction obliquely inclined by a predetermined angle with respect to the vertical axis of the mask plate. In addition, it is preferable that emissions of a plurality of parallel ultraviolet-ray laser beams with high energy are arranged so as to be incident in a direction equally divided with respect to the peripheral direction of the vertical axis of the mask plate.
In a method for manufacturing a liquid jet recording head according to the present invention, it is preferable that parallel ultraviolet-ray laser beams with high energy each are composed of four luminous fluxes, and are emitted in a direction equally divided with respect to the peripheral direction of the vertical axis, the beams each being obliquely inclined by a predetermined angle with respect to the vertical angle of the mask plate.
According to the present invention, an integral effect is achieved by non-uniform emission of ultraviolet-ray laser beams, thereby making it possible to perform ultraviolet-ray laser beam emission for each discharge nozzle in the same manner and predetermined conditions. As a result, all of the discharge nozzles are processed in uniform shape, whereby the recording liquid droplets can be jetted constantly and accurately, enabling high quality printing.
Further, the discharge nozzle can be processed and formed in the final process after the liquid jet recording head has been assembled, thereby eliminating the anisotropy in the liquid ejection direction caused by deformation due to assembling and bonding of the ejection orifice forming plate. In addition, a convergent taper-shaped discharge nozzle can be formed at the liquid ejection side (outside) of the ejection orifice forming plate, whereby the liquid droplet ejection direction is stable in a constant direction, and the jetting speed of the recording liquid to be discharged is improved. Therefore, a high resolution image having extremely reduced mist and clear circular print dots is obtained, whereby a print quality of the liquid jet recording head is remarkably improved, and fast printing is enabled.